package cn.maxhou.util;

import java.util.ArrayList;
import java.util.List;

public class Page<T> {
    //当前页码
    private Integer pageNo=1;
    //每页数量
    private Integer pageSize=5;
    //总数据量
    private Integer totalCount=null;
    //总页数
    private Integer totalPageCount=1;
    //分页数据集合,使用泛型兼容任意类型
    private List<T> data;

    public Integer getPageNo() {
        return pageNo;
    }

    public void setPageNo(Integer pageNo) {
        if(pageNo<=0){
            pageNo=1;
        }
        if(totalCount!=null){
            //计算过总页数后,页码的设置要参考总页数
            if(totalPageCount>=1 &&pageNo>totalPageCount){
                pageNo=totalPageCount;
            }
        }
        this.pageNo = pageNo;
    }

    public Integer getPageSize() {
        return pageSize;
    }

    public void setPageSize(Integer pageSize) {
        this.pageSize = pageSize;
    }

    public Integer getTotalCount() {
        return totalCount;
    }

    public void setTotalCount(Integer totalCount) {
        this.totalCount = totalCount;
        this.totalPageCount = this.totalCount %this.pageSize==0?this.totalCount/this.pageSize:this.totalCount/this.pageSize+1;
    }

    public Integer getTotalPageCount() {
        return totalPageCount;
    }

    public void setTotalPageCount(Integer totalPageCount) {
        this.totalPageCount = totalPageCount;
    }

    public List<T> getData() {
        return data;
    }

    public void setData(List<T> data) {
        this.data = data;
    }
    public int offset(){
        return (pageNo-1)*pageSize;
    }
    /**是否第一页*/
    public boolean isFirst(){
        return pageNo==1;
    }
    /**是否最后一页*/
    public boolean isLast(){
        return pageNo==totalCount;
    }
    /**是否还有下一页*/
    public boolean hasNext(){
        return pageNo<totalCount;
    }
    /**是否还有上一页*/
    public boolean hasPrevious(){
        return pageNo>1;
    }
    /**页面上显示指定长度的页码*/
    public List<Integer>getShowPageNos(int showCount){
        List<Integer> list = new ArrayList<Integer>();
        //先加中间页码
        list.add(pageNo);
        //每次页面计算步长
        int step=1;
        while (list.size()<showCount){
            boolean added=false;
            int left =pageNo-step;//左边减页码
            int right =pageNo+step;//右边加页码
            if (left>=1){
                //左边大于等于可以添加
                list.add(0,left);
                added=true;
            }
            if (right<=totalPageCount){
                //右边小于等于总数可以添加
                list.add(right);
                added=true;
            }
            if (!added){
                //如果左右都没添加成功,则退出
                break;
            }
            //下次循环增加步长
            step++;
        }
        return list;
    }
}
